A subset of late infiltrating neutrophils have a unique transcriptome of alternative activation associated with their pro-regenerative capacity 

ABSTRACT: Recent studies using advanced techniques such as single cell RNA sequencing (scRNAseq), high parameter flow cytometry, and proteomics have revealed that neutrophils are more heterogeneous than previously thought. Unique subsets have been identified in the context of bacterial and parasitic infections, cancer and tissue injury and repair. The diversity of subsets that predominate the neutrophil infiltrate in each of these conditions appears dependent on the type of injury and timing of neutrophil involvement in the disease state. We previously described a subpopulation of immature Ly6Glow neutrophils that accumulate in the peritoneal cavity 3 days following intraperitoneal (i.p.) administration of the fungal cell wall extract, zymosan. In contrast, conventional, mature Ly6Ghi neutrophils dominate the peritoneal infiltrate 4 hours following i.p. zymosan injection. The 3 day Ly6Glow, but not 4 hour Ly6Ghi, neutrophils induce neurite outgrowth of explanted neurons in vitro. Furthermore, they drive axon regeneration in the optic nerve (ON) and spinal cord (SC) when adoptively transferred in proximity to the eye after ON crush injury or SC dorsal column transection, respectively. These pro-regenerative effects are mediated in part, by the production of the growth factors insulin-like growth factor-1 (IGF-1) and nerve growth factor (NGF). In the current study, we expand upon on our previous observations by performing an in-depth characterization of the zymosan-modulated neutrophil subsets through scRNAseq and high parameter flow cytometry. Circulating neutrophils, harvested from unmanipulated mice, were analyzed in parallel as a control. We found that each of the unfractionated neutrophil populations is diverse, composed of multiple distinct clusters. Zymosanmodulated 3-day Ly6Glow neutrophils contain a cluster that expresses neuroprotective growth factors in association with markers of alternative activation. Furthermore, the unfractionated neutrophil populations were analyzed by liquid chromatography/ mass spectrometry for proteomic analysis. This new proteomic data identified a wide variety of proteins and pathways that contribute to the alternative activation state of these pro-regenerative 3 day Ly6Glow neutrophils. Collectively, the data generated by the current study constitute another step towards pinpointing the identity and mechanisms of action of pro-regenerative, neuroprotective neutrophil subsets.

ORGANISM(S): Mus musculus

PROVIDER: GSE200445 | GEO | 2022/06/01

REPOSITORIES: GEO